［Objective］Acrylate latex films have limitations in film compactness，water absorption and thermal properties，which restrict their further application in waterborne coatings requiring high water resistance.［Methods］ A core-shell polyacrylate latex was prepared by seeded emulsion polymerization using rigid poly（methyl methacrylate）（PMMA）as the core polymer and flexible poly（butyl acrylate）（PBA）as the shell polymer. The effects of PMMA core particle size and content on theproperties of the composite latex films were systematically investigated.［Results］The construction of the core-shell structure was beneficial for improving the overall performance of the polyacrylate latex.The water absorption of the latex films first decreased and then increased with the increase of PMMAcore particle size and PMMA content. When the PMMA core particle size was 98. 3 nm and the PMMA content was 30%，the composite latex film exhibited the densest structure and the best water resistance.After the conventional emulsifier was replaced with a reactive emulsifier，the water absorption of the composite latex film was further reduced to 11. 11%.［Conclusion］The particle size and content ofPMMA cores significantly affected the properties of the composite latex films. The compactness andwater resistance of the latex films could be improved by adjusting these parameters and furtherintroducing a reactive emulsifier.